In the field of production system of resin mold, generally applied is a system such that a powdered or granular material is supplied to a dryer from a powdered or granular material (thermoplastic resin pellet) tank and the dried powdered or granular material is pneumatically transported to a supply port (material part) of a molding machine. A feeding system is that the thermoplastic resin pellet as a row material is sucked to be transported from a stockyard, is collected in a collector, and is supplied to a heating dryer serving as a service hopper which is directly connected to the material supply port of the molding machine. The reference 1 is Utility Model No. 3058778 registered by the present applicant which discloses a pneumatic, automatic and continuous dehumidifying and drying apparatus of powdered or granular material to be used for the above-mentioned feeding system. According to the apparatus, resin pellet is sequentially fed in a molding machine while being dehumidified and dried, thereby largely improving the efficiency of production system of resin mold.
According to the above-mentioned feeding system, a material feed nozzle is inserted in the resin pellet piled up in a stockyard and the resin pellet is sucked to be transported to the above-mentioned dehumidifying and drying apparatus. Therefore, it is sufficient for the dehumidifying and drying apparatus serving as a service hopper to have a containing capacity for temporally storing the material corresponding to the capacity of molding machine and the capacity of heating means and so on is appropriately determined so as to adequately dehumidify and dry the material while storage.
The resin pellet as a raw material is generally brought in a form of a craft bag per 25 kg unit, a predetermined transportation unit, and it may be efficient to supply it as it is to a feeding apparatus. However, a small molding machine with molding capacity of 1000 g/hr has a drying capacity for about 4 kg, therefore, the above-mentioned dehumidifying and drying apparatus serving as a service hopper does not have such capacity to contain 25 kg of resin pellet at a time. The containing capacity may be correspondingly enlarged, however, the capacity of heating apparatus and so on should be enlarged. Because of the processing capacity (1000 g/hr) of such kind of resin molding machine, it is no need to always heat all of the 25 kg of resin pellet. Therefore, there arises a problem such that heating incurs waste, the apparatus becomes expensive and its running cost becomes high.